• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.1
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• pp.15-31
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• 2013

This paper proposes an intermediate image generation method for the viewer's view point by tracking the viewer's face, which is converted to a digital hologram. Its purpose is to increase the viewing angle of a digital hologram, which is gathering higher and higher interest these days. The method assumes that the image information for the leftmost and the rightmost view points within the viewing angle to be controlled are given. It uses a stereo-matching method between the leftmost and the rightmost depth images to obtain the pseudo-disparity increment per depth value. With this increment, the positional informations from both the leftmost view point and the rightmost view point are generated, which are blended to get the information at the wanted intermediate viewpoint. The occurrable dis-occlusion region in this case is defined and a inpainting method is proposed. The results from implementing and experimenting this method showed that the average image qualities of the generated depth and RGB image were 33.83[dB] and 29.5[dB], respectively, and the average execution time was 250[ms] per frame. Also, we propose a prototype system to service digital hologram interactively to the viewer by using the proposed intermediate view generation method. It includes the operations of data acquisition for the leftmost and the rightmost viewpoints, camera calibration and image rectification, intermediate view image generation, computer-generated hologram (CGH) generation, and reconstruction of the hologram image. This system is implemented in the LabView(R) environments, in which CGH generation and hologram image reconstruction are implemented with GPGPUs, while others are implemented in software. The implemented system showed the execution speed to process about 5 frames per second.

• Journal of Korea Multimedia Society
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• v.20 no.6
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• pp.865-872
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• 2017

Recent advance in electronics and scintillators makes it possible to utilize the time-of-flight (TOF) information in improving image reconstruction of positron emission tomography(PET). In this paper, we propose a TOF-based fast image reconstruction method for PET. The proposed method uses the deconvolution of TOF data for each angle view and the rotational averaging of deconvolved images. Simulation results show an improved performance of the proposed method, as compared with filtered backprojection (FBP) method, TOF-FBP, and TOF version of expectation-maximization(EM) methods. Simulation results also show a great potentiality of the proposed method in limited angle tomography applications.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.578-582
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• 2009

Computer-Generated Hologram (CGH) is generally made by Fourier Transform. CGH is made by an optical reconstruction. Computer-Generated Pseudo Hologram (CGPH) is made up Complex Hadamard Transform instead of CGH which is made by the Fourier Transform. CGPH differs from CGH in point of view the possibility of optical reconstruction. There is an advantage that it cannot be optical reconstruction, in other word, physical leakage of the confidential information is impossible. In this paper, a binary image was converted in Complex Hadamard Transform, and CGPH was made. Improvement of the reconstructed image from CGPH is done by error diffusion method and iterative method. The result that the reconstructed image is improved is shown.

• Applied Microscopy
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• v.46 no.2
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• pp.71-75
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• 2016

The scanning electron microscope (SEM) offers two-dimensional (2D) micrographs of three-dimensional (3D) objects due to its inherent operating mechanisms. To overcome this limitation, other devices have been used for quantitative morphological analysis. Many efforts have been made on the applications of software-based approaches to 3D reconstruction and measurements by SEM. Based on the acquisition of two stereo images, a multi-view technique consists of two parts: (i) geometric calibration and (ii) image matching. Quantitative morphological parameters such as height and depth could be nondestructively measured by SEM combined with special software programs. It is also possible to obtain conventional surface parameters such as roughness and volume of biomedical specimens through 3D SEM surface reconstruction. There is growing evidence that conventional 2D SEM without special electron detectors can be transformed to 3D SEM for quantitative measurements in biomedical research.

• Proceedings of the Optical Society of Korea Conference
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• 2009.02a
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• pp.167-168
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• 2009

We propose a new computing method for Fourier hologram of 3D objects captured by lens array. Fourier hologram of the two objects which positioned at different distances can be calculated using multiple orthographic view images. The size of the Fourier hologram is in proportion to the number of the orthographic view images. By repeating the orthographic view images, the size of the Fourier hologram can be increased. The principle is verified by numerically reconstructing the hologram which is synthesized from the orthographic images captured optically.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1611-1614
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• 2005

In this paper, a new multi-view 3D video communication system for real-time Reality teleconferencing application is proposed by usin gthe IEEE 1394 digital cameras, Intel Xeon server computer system and Microsoft's DirectShow programming library and its performance is analyzed in terms of image-grabbing frame rate and number of views. The captured two-view image data is compressed by extraction of disparity data between them and transmitted to another client system through the communication network, in which multi-view could be synthesized with this received 2-view data using the intermediate view reconstruction technique and displayed on the multi-view 3D display system. From some experimental results, it is found that the proposed system can display 16-view 3D images with a gray of 8bits and a frame rate of 15fps.

• Archives of Plastic Surgery
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• v.35 no.2
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• pp.152-158
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• 2008

Purpose: Mandibulotomy approach and mandible sparing approach are most common methods for oropharyngeal cancer surgery. Good surgical view and convenience of flap inset are advantages of mandibulotomy approach but deformity of mandible contour, postoperative malocclusion and radionecrosis are its limitations. To make up for the limitations, mandible sparing method is commonly performed, but limited surgical view and difficulties of flap inset are the weak points of this approach. The purpose of the study is to compare mandibulotomy and mandible sparing approaches in postoperative complications and progression of the treatment in oropharyngeal cancer operation and reconstruction. Methods: Single reconstructive microsurgeon operated for oropharyngeal cancer patients with different surgeons of head and neck department who prefer mandibulotomy and mandible sparing approach respectively, and we compared the frequency of postoperative complication, operation time, duration of hospitalization and recurrence rate between two different surgical approaches. Results: Mandibulotomy approach was used in 18 patients and mandible sparing approach was used in 15 patients. In mandibulotomy approach, there happened one case of teeth injury and one case of necrosis of skin and gingiva, but there happened no malocclusion and radionecrosis. In mandible sparing approach, there were 3 cases of fistula and 2 cases of infection which are significantly higher than mandibulotomy approach. There were no significant differences between early regional recurrence and duration of hospitalization. Conclusion: In this study we compared two different methods for the surgical approach in oropharyngeal cancer surgery. As mandible sparing approach has difficulties of limited surgical view, it can be used for the limited indications of anterior tongue and mouth floor cancer. Mandibulotomy approach has advantages of good surgical view and convenience of flap inset. In this method preservation of gingival tissue, watertight fashion suture, delicate osteotomy and plate fixation to maintain occlusion are the key points for the successful results.

• Journal of Gastric Cancer
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• v.13 no.1
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• pp.34-43
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• 2013

Purpose: The intracorporeal reconstruction after laparoscopic gastrectomy can minimize postoperative pain, and give better cosmetic effect, while it may have technical difficulties and require the learning curve. This study aimed to analyze the surgical outcome of intracorporeal reconstruction according to the surgeon's experience comparing with extracorporeal procedure. Materials and Methods: From January 2009 to September 2011, intracorporeal reconstruction in laparoscopic surgery for gastric cancer was performed for 71 patients (Intra group). During same period, 231 patients underwent laparoscopy-assisted gastrectomy (Extra group). These patients were classified into initial (1st to 20th case of intra group), intermediate (21th to 46th case), and experienced (after 47th case) phases. Results: Intracorporeal procedures included 35 cases of Billroth-I, 30 Billroth-II and 6 Roux en Y reconstructions. In the initial phase, operation time (P=0.022) were significantly longer for the patients of intra group than them of extra group. Although the difference was not significant, the length of hospital stay was longer and complication rate was higher in the intra group. In intermediate and experienced phases, there was no difference between two groups in operation time and hospital stay. In these phases, complication rate was lower in the intra group than the extra group (3.9% versus 9.7%). The pain scale was significantly lower post operation day 5 in the intra group. Conclusions: Intracorporeal reconstruction after laparoscopic distal gastrectomy was feasible and safe, and the technique was stabilized after 20th case if the surgeon has sufficient experiences when we compared it with extracorporeal reconstruction.

• The Journal of the Korea Contents Association
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• v.8 no.2
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• pp.74-82
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• 2008

This paper investigates chrominance reconstruction methods that reconstruct subsampled chrominance information efficiently using the correlation between luminance and chrominance components in the decompression process of compressed images, and analyzes drawbacks involved in the adaptive-weighted 2-dimensional linear interpolation among the methods, which shows higher efficiency in the view of computational complexity than other methods. To improve the drawback that the spatial frequency distribution is not considered for the decompressed image and to support the application on a low-performance system in behalf of 2-dimensional linear interpolation, this paper proposes the multi-mode reconstruction method which uses three reconstruction methods having different computational complexity from each other according to the degree of edge response of luminance component. The performance evaluation on a development platform for embedded systems showed that the proposed reconstruction method supports the similar level of image quality for decompressed images while reducing the overall computation time for chrominance reconstruction in comparison with the 2-dimensional linear interpolation.

• Journal of Korean Orthopaedic Sports Medicine
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• v.11 no.1
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• pp.57-61
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• 2012

Pretibial cyst formation is a rare complication after anterior cruciate ligament (ACL) reconstruction and there are only few cases reported. Pretibial cyst can be caused by variable reasons. Foreign body reaction due to breakdown of bio-absorbable screw for fixation, graft necrosis at tibial site, joint fluid leakage to tunnel and incomplete incorporation of graft to bony tunnel. The authors experienced one case of massive pretibial cyst after arthroscopic ACL reconstruction using bio-absorbable interference screw in 38-year-old male patient. Thus, authors report this rare case with literature view.